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### 3. Library calls (functions within program libraries)

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# CARG

Section: Linux Programmer's Manual (3)
Updated: 2015-04-19

## NAME

carg, cargf, cargl - calculate the complex argument

## SYNOPSIS

#include <complex.h>

double carg(double complex z);
float cargf(float complex z);
long double cargl(long double complex z);

## DESCRIPTION

These functions calculate the complex argument (also called phase angle) of z, with a branch cut along the negative real axis.

A complex number can be described by two real coordinates. One may use rectangular coordinates and gets

```    z = x + I * y
```

where x = creal(z) and y = cimag(z).

Or one may use polar coordinates and gets

```
z = r * cexp(I * a)

```
where r = cabs(z) is the "radius", the "modulus", the absolute value of z, and a = carg(z) is the "phase angle", the argument of z.

One has:

```
tan(carg(z)) = cimag(z) / creal(z)
```

## RETURN VALUE

The return value is the range of [-pi,pi].

## VERSIONS

These functions first appeared in glibc in version 2.1.

## ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
 Interface Attribute Value carg(), cargf(), cargl() Thread safety MT-Safe

## CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.

cabs(3), complex(7)

## COLOPHON

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NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
VERSIONS
ATTRIBUTES
CONFORMING TO